The present invention relates to a red color toner that is capable of high-chroma reproduction of red-color images produced with a variety of writing instruments and materials.
Color recording in electrophotography can be accomplished by the following two methods: full-color copying which is designed to reproduce the colors of an original by the combination of toners having the three primary colors for substractive mixing, that is, magenta, yellow and cyan; and monochromatic (flat-color) copying which employs a black color and at least one non-black color to record part or all of the original in separate colors.
Originals may be multi-colored and can only be reproduced by full-color copying; among such originals are color photos, painted pictures, and full-color drawings. The other type of originals employs a black color and one or more other colors and included within this category of originals are black-colored originals, containing seal impressions, stamp marks, sentences, illustrations, corrections and underlines. The second type of originals is more frequently used and those containing red colors find the most frequent use. The red-color images produced in such originals have different shades depending upon the writing instruments and material used, as shown in FIGS. 3 and 4, in which (1) refers to a vermillion inkpad for impressing a seal, (2) and (7) a marking pen, (3), (4), (5), (11) and (13) a ball-point pen, (8) a stamp, (9) an oily ink felt pen, (10) a chart drawing ink, (6), (12), (15) and (16) a felt pen, and (14) a water-based ink.
However, red images on originals having such a broad spectrum of shades cannot be satisfactorily reproduced with the full-color toners conventionally employed in full-color copying. For instance, high-chroma red colors cannot be reproduced even if the magenta toner described in Unexamined Published Japanese Patent Application No. 27228/1974 is used in combination with the yellow toner described in Unexamined Published Japanese patent Application No. 17023/1977. No red color toners have been known, either, that are successfully used in flat-color copying.